The IRS has issued final and temporary regulations (T.D. 9717) regarding the allocation of the section 41 research credit to businesses under common control. The regulations reflect changes made to section 41 by section 301(c) of the American Taxpayer Relief Act of 2012, P.L. 112-240, and generally reflect interim guidance previously provided in Notice 2013-20. The regulations also address the allocation of the railroad track maintenance credit and the election for a reduced research credit.